a.) The following questions refer to the optical cavity in the diagram below. It is excited by a variable frequency source and the detected intensity is displayed on an Optical Spectrum Analyzer. -VOUT & Power 125 MHz 2.5 MHz 5x101 Hz i) What is the nominal wavelength of the source? ii) Determine the length 'L' of the optical cavity. iii) A measure of the sharpness of the resonant optical cavity is the 'Q' Factor. Determine the Q Factor and the photon lifetime of this resonant optical cavity. iv) For this part, assume that the cavity is filled with an active medium with a single pass gain of y. Determine the value of y to ensure oscillation (resonance) in the cavity. b.) Quartz windows oriented at Brewster's angle are commonly used in Helium Neon lasers as shown below. Determine the orientation angle 0 of the window measured from the axis of the cavity. What is the purpose of the window? Which component of light is transmitted? Which component of light is reflected? 0=?